This is Python version 3.0 alpha 2

For notes specific to this release, see RELNOTES in this directory.

Python 3000 (a.k.a. "Py3k", and released as Python 3.0) is a new
version of the language, which is incompatible with the 2.x line of
releases. The language is mostly the same, but many details,
especially how built-in objects like dictionaries and strings work,
have changed considerably, and a lot of deprecated features have
finally been removed.

This is an ongoing project; the cleanup isn't expected to be complete
until some time in 2008. In particular there are plans to reorganize
the standard library namespace.

Release Schedule

The release plan is to have a series of alpha releases in 2007, beta
releases in 2008, and a final release in August 2008. The alpha
releases are primarily aimed at developers who want a sneak peek at
the new langauge, especially those folks who plan to port their code
to Python 3000. The hope is that by the time of the final release,
many 3rd party packages will already be available in a 3.0-compatible
form.

Documentation

The design documents for Python 3000 are also online. While the
reference documentation is being updated, the PEPs are often the best
source of information about new features. Start by reading PEP 3000:

What's New

We'll eventually have a comprehensive overview of the changes in a
"What's New in Python 3.0" document. Please help write it!

What's New Since 3.0a1

Undoubtedly the biggest change is in the bytes type: 'bytes' is now
immutable, and there is a new mutable bytes type 'bytearray'. These
two types are interoperable in every way. For more info on this
issue, read PEP 3137.

For a more detailed change log, read Misc/NEWS (though this file, too,
is incomplete, and also doesn't list anything merged in from the 2.6
release under development).

Converting From Python 2.x to 3.0

Python 2.6 (not yet released) will contain features to help locating
code that needs to be changed, such as optional warnings when
deprecated features are used, and backported versions of certain key
Python 3000 features.

A source-to-source translation tool, "2to3", can take care of the
mundane task of converting large amounts of source code. It is not a
complete solution but is complemented by the deprecation warnings in
2.6. This tool is currently available via the Subversion sandbox:

Build Instructions

You can pass many options to the configure script; run "./configure
--help" to find out more. On OSX and Cygwin, the executable is called
python.exe; elsewhere it's just python.

On Mac OS X, if you have configured Python with --enable-framework,
you should use "make frameworkinstall" to do the installation. Note
that this installs the Python executable in a place that is not
normally on your PATH, you may want to set up a symlink in
/usr/local/bin.

On Windows, see PCbuild/readme.txt.

If you wish, you can create a subdirectory and invoke configure from
there. For example:

mkdir debug
cd debug
../configure --with-pydebug
make
make test

(This will fail if you also built at the top-level directory. You
should do a "make clean" at the toplevel first.)